ABSTRACT
Figure 5.1 shows the MPECVD system used by Wu et al. [4, 6, 7, 32] to grow carbon nanowalls. It consists of a vertical quartz tube lo-cated inside a microwave cavity with a 500 W microwave source. Inside the quartz tube are two parallel plate electrodes, placed 2 cm away from each other in the longitudinal direction of the tube, for applying a DC bias during the growth. The gases used are mixtures of CH4 and H2. This specific system does not come with an independ-ent substrate heater, and the substrate temperature is controlled by the microwave power to be 650−700°C. Apart from the temperature, other important parameters which affect the growth of carbon na-nostructures are H2/CH4 flow rate ratio and electrical field. The latter consists of both a global DC field, adjustable by the applied DC bias, and a localized AC field due to the plasma itself. The local elec-
trical field plays an important role in determining the orientation of the individual pieces of carbon nanowalls [5].
